1. Technical Field
The present invention teaches a cylinder lock arrangement. More particularly, the present invention teaches a cylinder lock arrangement comprising a cylinder housing attached to a door and a lock cylinder with lever tumbler provided to cooperate with a lock device, whereby the lock device is affectable via a carrier provided to the cylinder lock.
2. Background Information
In conventional cylinder locks a lock cylinder with lever tumbler is provided in a cylindrical housing, whereby the lever tumblers in locking position extend from the lock cylinder and are in engagement with recesses in the cylindrical housing. In these known locks the lock cylinder is connected to a carrier, which in turn is connected to the lock device.
When a fitting key is inserted in the keyhole the lever tumblers are displaced so that they disengage with the cylindrical housing. The lock cylinder thus becomes rotatable inside the cylindrical housing for operation of the lock device.
If a wrong key or a tool is inserted in the keyhole, the lock cylinder can only be rotated together with the cylindrical housing. Accordingly, by reinforcing the attachment of the cylindrical housing this type of lock can make it more difficult to commit burglaries. However, for vehicle locks it is difficult to provide sufficient reinforcements due to increases in costs and vehicle weight.
It is previously known to provide overload connections in vehicle locks that break the connection between the lock cylinder and the carrier at great torques. These connections intentionally break when somebody violently tries to rotate the lock cylinder without using the right key.
A cylinder lock with overload connection is described in German publication DE 44 10 736 A1. In that lock, the cylindrical housing is displaced in relation to the lock cylinder during overload. This displacement is utilized to break the connection between the lock cylinder and the carrier. The displacement, and thus disconnection of the carrier, remains until the right key is inserted in the lock cylinder.
The present invention discloses a device that further improves theft protection. In order to accomplish this, the invention provides for a connection device for the transmission of force from a lock cylinder to a carrier. When the lock cylinder is rotated by a fitting key, the connection device is axially displaced from a neutral position relative to the lock cylinder and in the direction of the lock cylinder. Not until after axial displacement from the neutral position is the connection device brought to an active position in friction engagement with the carrier. Locking and unlocking of the lock device may then be respectively performed by further rotation of the lock cylinder by the key. During a return movement of the key, the connection device is brought back in an axial direction to the neutral position. The connection device is then disengaged from the carrier.
An advantage with the device of the present invention is that the lock cylinder, when in the normal position, is always is in engagement with the carrier. Not until the right key is inserted and rotated a distance is the lock cylinder mechanically connected to the carrier.
In known cylinder locks with overload connections, the lock cylinder is initially mechanically connected to the carrier. Compared to the present invention, this increases the possibility of breaking open the lock.
A considerable advantage of the device of the present invention is that a connection device having a friction surface, which is situated on the opposite side of the carrier in relation to the lock cylinder, must be pulled in the direction towards the lock cylinder for connection of the friction resurface to a friction surface on the carrier before the lock device can be actuated via the lock cylinder. Because of this, the lock according to the invention is practically impossible to break open via the keyhole.
Other advantages with the device according to the invention is that the construction of the lock is relatively simple and it does not need to be designed in strong materials and in great dimensions to be theft proof. The device according to the invention can be manufactured in plastics, which makes the lock according to the invention economically advantageous in relation to conventional locks, while also eliminating corrosion problems.